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Biomedical subjects

J R Stevens

Publications and source records attributed to J R Stevens.

At least 73 records · Page 4Linked to original sources
PubMed1989

Isoenzyme characterization of Trypanosoma evansi isolated from capybaras and dogs in Brazil.

Trypanosoma evansi was seen in blood samples taken randomly from both wild and semi-captive capybaras caught in Mato Grosso do Sul State, Brazil and in sick dogs brought into local veterinary clinics. Trypanosome stocks from capybaras and dogs were significantly different in their patterns of growth in mice, while the trypanosomes from dogs were mostly dyskinetoplastic. By isoenzyme electrophoresis all the trypanosomes were of the most common type of T. evansi found elsewhere.

Animals↗
PubMed1988

The expression of phosphorylated neurofilament epitopes in human brains.

The expression of phosphorylated neurofilaments (PNF) epitopes in hippocampal neurons was examined in 5 cases of Alzheimer's disease and 12 brains of schizophrenic patients. A control group (n = 17) consisted of 5 brains of patients with other acute or chronic neurologic disorders and 12 brains of persons who were free of any known neurologic disease. Immunocytochemistry with monoclonal antibodies to PNF was done on formalin-fixed, paraffin sections of hippocampus. Adjacent sections were impregnated with silver. Immunoreactivity to PNF was observed in tangles and plaques of the Alzheimer's brains and also in hippocampal pyramidal cells in 6 of the 12 schizophrenic brains and in 9 of the 17 control brains (2 with neurological disorders and 7 with non-neurological diseases). The positive PNF-stained cell bodies, in silver impregnated sections, generally did not show evident neurofibrillary abnormalities. Enzymatic dephosphorylation prior to immunostaining abolished PNF reactivity. These results suggest the widespread occurrence and relative non-specificity of perikaryonal PNF immunoreactivity in human post mortem brain tissue. We could not exclude the possibility that the hippocampal and brainstem neurons are predilection sites for normal perikaryonal phosphorylation in human brain.

Adult↗
PubMed1988

Intracerebral inoculation of experimental animals with brain tissue from patients with schizophrenia. Failure to observe consistent or specific behavioral and neuropathological effects.

To test the possibility that some cases of schizophrenia result from infection with a transmissible slow viral agent, 57 experimental animals (six chimpanzees, 12 Old World monkeys, 17 New World monkeys, and 22 guinea pigs) were inoculated intracerebrally with brain tissue from ten patients and followed up for six years. Behavioral comparisons with control animals revealed no consistent behavioral differences. Histological, immunohistochemical, and morphometric examination of brains of animals that died revealed no specific neuropathological abnormalities. These findings do not support a role for a virus-induced slow infection in the pathogenesis of schizophrenia but must be weighed against methodological limitations in animal susceptibility, disease communicability, and assay sensitivity.

Adult↗
PubMed1988

Light transducer for the biological clock: a function for rapid eye movements.

To test the hypothesis that the rapid eye movements (REMs) of paradoxical sleep (PS) transmit information about environmental light: dark cycles, spontaneous locomotor patterns were studied in rats following surgical disconnection of the extraocular muscles and thus deprived only of the eye movement component of REM sleep. Entrainment of the circadian spontaneous activity cycle to the light: dark cycle was abolished after sectioning the extra-ocular muscles of rats, but not in sham-operated controls. Endogenous (free running) circadian patterns of spontaneous activity were preserved in the operated animals. The results are consistent with our electrophysiologic studies showing that REMs induce light modulated electrical potentials in brain regions that influence circadian rhythms of activity.

Animals↗
PubMed1988

Schizophrenia and multiple sclerosis.

Similarities in clinical course, age of onset, geographical distribution, and immunological responses of patients with schizophrenia and multiple sclerosis (MS) suggest that these two common illnesses of young adults may belong to a similar class of disorders. This review examines some of the similarities and differences between these two disorders and suggests that epidemiological, immunological, and viral studies considered useful in the investigation of causal factors in multiple sclerosis may also be pertinent to the search for causes of schizophrenia.

Humans↗
PubMed1988

Psychiatric aspects of epilepsy.

The frequency of severe psychiatric disorders in patients with epilepsy depends first and foremost on what populations of patients are studied. In random surveys seeking prevalence of epilepsy in the community, the prevalence of associated psychiatric disorder is low. In specialty referral clinics for epilepsy, particularly those serving indigent populations, the prevalence is 25% to 50%. Among epileptics in mental hospitals or psychiatric clinics, the prevalence is, naturally, 100%. This discussion is focused on the evidence for a causal or physiological relationship between epilepsy and psychosis, depression, aggression, and sexual disturbances, and treatment of these disorders. Particular attention is given to possible relationships between temporal lobe (limbic) epilepsy and schizophrenic disorders.

Cross-Sectional Studies↗
PubMed1987

Long survival in B-CLL correlates with surface IgM kappa phenotype.

200 patients with B-cell chronic lymphocytic leukaemia (B-CLL) presenting to a single centre over 13 years have been studied. In 72.2% the diagnosis was made on an incidental blood count, and 70.1% were stage A at presentation. Those patients whose cells expressed surface IgM kappa were significantly more likely to be stage A at presentation and significantly less likely to have a lymphocyte count greater than 50 X 10(9)/l, to have progressive disease or to require treatment than those with other classes of surface Ig. Patients whose cells express surface IgM kappa have a significantly longer actuarial survival than others and this is also so when only patients in Binet stage A or when only patients presenting below the age of 75 are studied. By studying all of the cases presenting in a single catchment area we have attempted to avoid the bias against trivial disease likely to be seen in specialist referral centres.

Adult↗
PubMed1985

Myelodysplastic syndromes: a scoring system with prognostic significance.

141 patients with MDS were classified according to the FAB criteria and followed up for a period of 4-192 months. It was recognized that patients with RAEBT had a uniformly poor prognosis. However, there was a wide variation in survival among the other subgroups. A score of 1 was assigned to each of the following presenting haematological features: bone marrow blasts greater than or equal to 5%, platelets less than or equal to 100 X 10(9)/l, neutrophils less than or equal to 2.5 X 10(9)/l and Hb less than or equal to 10.0 g/dl. Therefore the score for each patient ranged between 0 and 4. There were no statistically significant differences between those patients who scored 0 or 1, or between those who scored 2 and 3. Therefore patients were put into three groups: Group A (score 0 or 1), Group B (score 2 or 3), Group C (score 4). The differences in survival between each of the three groups are highly significant (P less than 0.00001). This system further separates patients with RA, RAS, RAEB into good and bad prognostic groups. This study also confirms that deaths due to cytopenias are more common than those due to transformation to AML. The use of this scoring system in conjunction with the FAB criteria for MDS should serve as a prognostic tool on which to base treatment.

Aged↗
PubMed1984

A search for cytomegalovirus and herpes viral antigen in brains of schizophrenic patients.

The peroxidase-antiperoxidase method was employed to search for evidence of cytomegalovirus (CMV) or herpes simplex virus (HSV) antigen in the brains of 25 patients with a diagnosis of schizophrenia, 25 nonschizophrenic neuropsychiatric patients, and 16 nonpsychiatric control subjects. Brain specimens from patients with acute CMV and herpes encephalitis served as positive controls. Although early results with low-titer CMV antisera suggested immunoreactivity in specific brain regions of a small number of schizophrenic and control cases, the present studies with high-titer anti-CMV IgG did not give a positive immunoperoxidase reaction in sections from the basal forebrain, hypothalamus, or midbrain. Scattered neurons in the lateral vestibular nucleus and hippocampus showed questionable staining with CMV IgG in one schizophrenic patient and none in control subjects. No schizophrenic or control cases demonstrated an immune reaction to HSV antisera.

Adult↗